You may not know what a “Sankey diagram” is, but you’ve almost certainly seen them before. They’re a specific way of visualizing how things flow from one state to another, and in what quantities. The classic infographic of Napoleon’s disastrous march to Moscow is a Sankey diagram: It starts out with a big thick band that narrows and splits off to illustrate how many soldiers died and deserted along the route. Sankey diagrams, while beautiful, are pretty labor-intensive to make. But now there’s a free web application called Fineo that can auto-generate one of these babies out of whatever data you upload into it.

Density Design created Fineo to solve its own internal problem: “We needed a generative and
streamlined way to create this kind of visualization,” Paolo Ciuccarelli, Density’s scientific director, tells Co.Design via email. “Then other people/scholars/researchers found it useful, and this convinced us to share it in a more public way.” Ciuccarelli says that Density is planning to keep Fineo “completely free” even as they continue to refine its performance.

Nathan Yau of FlowingData has quibbled with Fineo’s definition of what constitutes a “true” Sankey diagram, but the tool was apparently good enough for the researchers at Stanford’s Mapping the Republic of Letters project; Ciuccarelli says that they used Fineo internally as a visualization tool.

So what good is Fineo for the rest of us? Even as an imperfect prototype, it’s pretty darn cool for exploring the basics of data visualization firsthand — in other words, a great interactive teaching tool. It could even appeal to someone who just wants to turn data into visual art without too much “process” getting in the way: upload some .csv files, see what happens, repeat. Is that so wrong?